Process for catalyzed abnormal addition reactions



' captans and/or secondary thio-ethers.

Patented Dec. 3, 1946 NITED STTES PROCESS FOR CATALYZEI) ABNORMALADDITION REACTIONS of Delaware No Drawing. Application June 24, 1044,

Serial No. 542,028

This invention relates toan improved method for the addition of hydrogensulfide and/or mercaptans to symmetrical or unsymmetrical organiccompounds containing one or more unsaturated linkages of aliphaticcharacter. In one of its more specific embodiments, the inventionpertains to a novel method of effecting a controlled reaction betweenhydrogen sulfide or a mercaptan and unsymmetrical organic compoundscontaining at least one unsaturated linkage of aliphatic character, i.e. an olefinic or acetylenic bond, to produce. addition products ofpredetermined character.

This application is a continuation-in-part of the copending application,Serial No. 432,049,

filed February 23, 1942, now Patent No. 2,398,481, dated April'16, 1946.

It is known that mercaptans and thio-ethers may be produced by reactinghydrogen sulfide or a suitable mercaptan with an unsaturated organiccompound, e, g. unsaturated hydrocarbon, at elevated temperatures in theapproximate range of from 200 C. to 750 C. In some cases such reactionswere eiiected at superatmospheric pressures. When hydrogen sulfide isreacted with unsaturated organic compounds under the outlinedconditions, the sulfhydryl group attaches to the unsaturated carbon atomcontaining the lesser number of hydrogen atoms attached thereto, sothat, as clearly brought out by Jones and Reid (Journal AmericanChemical Society, vol. 60, pp. 2452-2455), the addition takes placeaccording to Markownikofi's rule. Therefore, when terminally unsaturatedolefins are thus reacted with hydrogen sulfide, the reaction productpredominates in secondary mer- When the unsaturated organic compoundshave been reacted with the mercaptans at the aforementioned elevatedtemperatures, the sulfur atom of the mercapto radical attachedpredominantly to the unsaturated carbon atom holding the most hydrogenatoms so that this addition was contrary to the course suggested by theMarkownikofi rule. This condition was designated as "abnormal additionon the assumption that mercaptans should add like halogen acids. Withreference to the addition of mercaptans to unsaturated organiccompounds, it is known that the abnormal addition may be catalyzed byfree oxygen, air, ozone, peroxides, ascaridole, and the like, whilecompounds of the type of hydroquinone and piperidine act as reactioninhibitors.

It has been recently discovered that hydrogen sulfide may be added tounsaturated organic 13 Claims. (01.204-163) compounds, contrary to thecourse suggested by the Markownikofi rule, by effecting the reaction atnormal temperatures or even at considerably lower temperatures, underthe deliberate infiuence of ultraviolet radiations having wavelengths ofbelow about 2900 to 3000 Angstrom units. It is known that the presenceof peroxides or of peroxide-forming compounds in unsaturated organiccompounds, e. g. unsaturated hydrocarbons, is undesirable. The processesinvolving the abnormal addition of hydrogen sulfide and/or of mercaptansto unsaturated organic compounds under the deliberate influence ofultraviolet radiations necessitate the use of special equipment which iscapable of transmitting rays of the defined low wavelengths. In otherwords, in order to effect the desired reaction it is necessary to employreaction vessels and/or lamps of quartz or other suitable materials, e.g. calcium fluoride, which are capable of transmitting the defined shortwavelengths of 2900 to 3000 Angstrom units and below.

It has now been discovered that unsaturated organic compounds of theclass more fully described herelnbelow may be reacted with hydrogensulfide or mercaptans to effect directional addition thereof via theabove-defined abnormal addition, this reaction being efiected withoutthe necessity of resorting to high temperatures and/or elevatedpressures, and in the absence of undesirable peroxides orperoxideforming compounds. It has also been discovered that thisreaction according to this invention may be effected without thenecessity of employing any special equipment or apparatus capable oftransmitting very low ultraviolet rays, such as radiations 'havingwavelengths of 2900 to 3000 Angstrom units or below. According tothepresent process, this abnormal addition of hydrogen sulfide or ofmercaptans is attained by effecting the reaction under. irradiatingconditions (and particularly under the deliberate influence of rayswhich will not otherwise dissociate any one of the reactants), and inthe presence of certain catalysts having definite and specificcharacteristics which promote the abnormal addition but the presence ofwhich in the unsaturated organic compounds is not detrimental. Generallyspeaking, these catalysts or reaction sensitizers comprise carbonyliccompounds which absorb light and which may thus be decomposedphotochemically by radiations having wavelengths of about 2900 to 3000Angstrom units and above.

It has also been discovered that catalysts or sensitizers of the classmore fully described here- 3 in and consisting of or comprisingcarbonylio compounds of the type defined'hereinbelow will catalyze andcontrol the reaction between an unsaturated organic compound and amercaptan or hydrogen sulfide so that the reaction will occur via theso-called "abnormal" addition at ordinary or even subnormal temperaturesand without the necessity of employing special equipment or apparatuswhich will transmit ultraviolet radiations having wavelengths of 2900 to3000 Angstrom units or below.

Broadly stated, the present invention resides in a photochemical processof effecting the addition of suitable mercaptans or hydrogen sulfide inthe presence of carbonylic compounds and under the deliberate influenceof light capableof photochemically dissociating said catalyst orsensitizer, this reaction being eflected at normal temperatures, i. e.in the neighborhood of from about 25 C. to about 15 C., or even atconsiderably lower temperatures. This photochemical addition occurscontrary to the course suggested 'by Markownikoff for the addition ofhydrogen halides, and in accordance with the rule proposed by Posner(Berichte, vol. 3 p. 646 (1904)) concerning the addition of mercaptansto double bonds.

The unsaturated organic compounds which may be treated according to theprocess of this invention include hydrocarbons containing one or moreolefinic and/or acetylenic linkages. Examples of such hydrocarbons areethylene, propylene, butene-l, butene-Z, isobutylene, pentene- 1,pentene-2, hexane-1, 4-methyl-pentene-l, 4,4- dimethylpentene-l,4-methyl-pentene-2, octenel, decene-l, cetene-l, styrene, cyclohexene,3- methyl-cyclohexene, 1,4-diphenyl-butene-2, butadiene-LZi,pentadiene-1,3, pentadiene-l,4, hexadiene-1,5, hexadiene-IA, acetylene,propyne, butyne-l, pentyne-2, hexyne-l, cetyne-l, octylacetylene,phenyl-acetylene, cyclopentadiene, and the like. The above compounds,and their various homologues, may be substituted in the nucleus and/orin the substituents in varying degrees. For instance, the unsaturatesmay contain one or more halogen atoms attached to saturated and/orunsaturated carbon atoms. Representative examples of these compoundsare: vinyl halides, allyl halides, crotyl halides, methallyl halides,and the like. Other examples or substituted unsaturated hydrocarbons aremethyl acrylate, methyl methacrylate, divinyl ether, diallyl ether,dimethallyl ether, and the like.

A particularly suitable group of organic compounds which may be reactedwith mercaptans or hydrogen sulfide via abnormal addition comprises thecompounds, and particularly the hydrocarbons, in which the unsaturatedlinkage is in terminal or alpha position. Also, aliphatic hydrocarbonsand their various substituted derivatives, e. g. halosubstitutedderivatives, containing unsaturated linkages both in alpha and omegapositions (i. e. terminal positions), may be readily reacted with theabove-outlined compounds, via

-.abnormal addition, to produce compounds in which both terminal carbonatoms have sulfhy- (11171 or mercapto radicals attached thereto. Anothergroup of organic compounds which may be employed as the primary materialcomprises or includes organic compounds wherein an oleflnic linkage isin non-terminal position between two carbon atoms having a dissimilarnumber of hydrogen atoms attached to each of said unsaturated carbonatoms due, for example, to various substituents attached thereto. Forinstance, the

double bond may be between two carbon atoms which are of secondary andtertiary character, respectively. Another example is a compound in whichthe unsaturated carbon atoms are both primary or both secondary, buthave unequal numbers of halogen atoms, such as chlorine, bromine,fluorine and/or iodine atoms attached to them.

Any sufiiciently stable mercaptan is suitable as a reactant to beemployed in the photochemical addition thereof to the above-definedclass of unsaturated organic compounds. A suitable mercaptan may containone or more sulfhydryl groups or radicals, and be of alkyl, araikyl,alkenyl, aralkenyl or aryl character. The mercapto radical may be linkedto an aliphatic or an aromatic carbon atom, In the majority of casesitis preferable to employ the normal or iso alkyl chain mercaptans. ofprimary, secondary or tertiary character, particularly those containedin or derived from petroleum and petroleum products. The methyl, ethyl,butyl, amyll, hexyl, heptyl, octyl and the like mercaptans, as well astheir homologues, analogues and substitution products, may be employedwith excellent results. Another group of mercaptans which. may beempioyed as one of the two reactants comprises or includes thedimercaptans, and particularly the polymethylene dimercaptans oi thegeneral'tormula HS(CH2)nSH. This group of mercaptans may be reactedwith, for example, aliphatic hydrocarbons containing a plurality ofunsaturated linkages to produce thio-ethers having a high molecularweight. g

As stated, the substances which may be used as catalysts or sensitizersfor the above-outlined .reaction, in which mercaptans orhydrogen'sulfide are added via abnormal addition, comprise thecarbonylic compounds, and particularly those which may be dissociated ordecomposed photochemically by moans of rays having wavelengths of about2900 to 3000 Angstrom units and longer. Without any intention ofbeinglimited by the compounds enumerated herein, it may be stated thatrepresentative compounds or this class include: aliphatic and aromaticketones, such as acetone, methyl ethyl ketone, methyl n-propyl ketone,methyl isopropyl ketone, diethyl ketone, ethyl n-propyl ketone, methyln-butyl ketone, di-

59 propyl ketone, acetophenone, and their homologues; aldehydes, such asacetaldehyde, propionaldehyde, isobutyraldehyde, benzaldehyde, and thelike, and their homologues; and acid halides, 'for' exampleacetylbromide, propionyl bromide,

and the like. It is to be understood that there is no intention ofcontending that all carbonylic compounds which are dissociable by lightmay be employed equally effectively as catalysts or sensitizers for thedescribed abnormal addition of meroo captans or hydrogen sulfide. Forexample, some of these carbonyiic compounds, in order to be dissociated,may require radiations oimuch shorter wavelengths than those necessary,for the decomposition of other carbonylic compounds. Also, the rate ofchain initiation of some carbonylic compounds, although they may bereadily decomposed photochemically by radiations of wavelengths above2900 Angstrom units, is considerably slower than the rate 01 chaininitiation of other carbonylic compounds. This may be due to sterichindrance or even resonance in the radical formed during thedecomposition. Nevertheless, it may be generally stated that allcarbonylic compounds, and particularly the ketones, aldehydes and acidhalides, which are capable of being dissociated by light havingwavelengths of about 2900 to 3000 Angstrom units, and longer, may beeiiectively used as catalysts or sensitizers for the desired abnormaladdition reaction.

The abnormal addition reaction between the defined compounds accordingto the process of the present invention may be effected in the vapor orliquid phase, or in a two-phase liquid-vapor mercaptans or hydrogensulfide, when the reaction is eifected under the influence of theabovedefined class of catalysts or sensitizers, proceeds regardless ofthe presence or absence of a liquid film in the reaction zone. Althoughthe reaction described herein may be promoted or effected by using thewhole range of ultraviolet radiations, it has been pointed out abovethat the presence of the defined catalysts or sensitizers (which,incidentally, do not have a detrimental eflecton the reactants)eliminates the necessity of using radiations having very shortwavelengths. In other words, whereas abnormal addition of, for example,hydrogen sulfide to an'unsaturated organic compound would requireultraviolet radiations having wavelengths of below about 2900 to 3000Angstrom units, the addition of even small amounts, e. g. from about 1%to about 10%, of a compound of the class of catalysts or sensitizersdefined above permits eiTective addition even when th radiations havelonger wavelengths, provided such rays will cause the initialdissociation of the catalyst or sensitizer, thereby initiating the chainmechanism, and at the same time directionally controlling the additionreaction.

The abnormal reaction according to the present process may be efiectedin a batch, intermittent or continuous manner. When the process isexecuted batchwise, the reactants, together with a suitable amount ofthe catalyst or sensitizer of the defined class, may be conveyed underany suitable or optimum pressure and temperature into a suitablecontainer which is then illuminated, preferably with ultraviolet light,for a period of time sufficient to efi'ect the desired additionreaction. Although containers oi quartz or the like may be employed, soas to permit light waves of between 2900 and 3000 Angstrom unitstherethrough, it is possible to employ ordinary glass or Pyrex glass,since wavelengths passing through this type of glass will alsodissociate the sensitizer or catalyst and thus initiate and 'efiect thedesired reaction.

Although there is' no intention of being lim-' ited by' any detailstherein, the following illustrative examples represent specificembodiments of the present invention.

Eaample I Example 11 The experiment described in Example I was repeated.However, prior to the sealing of the 'reactor, acetone was added in suchan amount that the volumetric ratio of propylene, hydrogen sulfide andacetone-in the reactor was 7.4:7.:l. After the six-minute illuminationthe reactionmixture was distilled to evaporate the unreacted compounds.It was then found that about 75% of the propylene reacted via abnormaladdition, the reaction roduct consisting of about weight percent ofnormal propyl mercaptan and about 20 weight percent of di-n-propylsulfide.

Example In When a substantially equivolumetric mixture of propylene andn-propyl mercaptan, which mixtur contains about 5% acetone, is disposedin a Pyrex glass container and is subjected at a temperature of about 0C. to the action of ultraviolet radiations emanating from a quartzmercury lamp, the reaction product contains appre-- cable amounts ofdi-n-propyl sulfide.

Example IV Propylene, hydrogen sulfide and acetaldehyde,

are introduced in the liquid state into a Pyrex glass container in suchamounts that the volumetric ratio of said ingredients is 12:12:1, andare maintained in said container at about 25 C.

The illumination of the mixture with ultraviolet radiations emanatingfrom a quartz mercury lamp' results in the formation of substantialamounts of n-propyl mercaptan and some di-npropyl sulfide.

Example V 7 When hexene- 1. is reacted with hydrogen sulfide in theresence of a minor amount of acetone and according to th processdescribed in Example II, the reaction product contains n-hexyl mercaptanand di-n-hexyl sulfide.

-We claim as our invention:

1. In a process of producing normal propyl mercaptan, the steps ofmixing propylene with hydrogen sulfide and withacetone, and eifectingthe reaction in the liquid state, at a temperature not in execess ofabout 25 0., and under the deliberate influence oi radiations above 3000Angstrom units but capable of dissociating acetone.

2. In a process of producing normal propyl mercaptan, the steps 01'mixing propylene with hydrogen sulfide and with acetaldehyde, andeffecting the reaction in the liquid state, at a temperature not inexcess of about 25 0., and under the deliberate influence of radiationsabove 3000 Angstrom units but capable of dissociating acetaldehyde.

3. In a process of effecting abnormal addition of hydrogen sulfide to analiphatic hydrocarbon containing an alpha unsaturated linkage, the stepsof adding an aliphatic ketone which is decomposed by light naving a wavelength above 3000 Angstrom units to the reaction mass, and effecting thereaction in the absence of peroxides, at a temperature not inexcess ofabout 25 C., and under the deliberate influence oi radiations above 3000Angstrom units but capable of dissociating the aliphatic ketone.

4. In a process of efiecting abnormal addition of hydrogen sulfide to analiphatic hydrocarbon containing an alpha unsaturated linkage, the

steps of adding a ketone which is decomposed by light having a wavelength above 3000 Angstrom units to the reaction mass, and efiecting thereaction in the absence of peroxides, at a temperature not in excess ofabout 25 C., and under the deliberate influence of radiations above 3000Angstrom units but capable of dissociating the ketone.

5. In a process of effecting abnormal addition of hydrogen sulfide to analiphatic hydrocarbon containing an alpha unsaturated linkage, the stepsof adding an aldehyde which is decomposed by light having a wave lengthabove 3000 Angstrom units to the reaction mass, and efiecting thereaction in the absence of peroxides, at a temperature not in excess ofabout 25 C., and under the deliberate influence of radiations above 3000Angstrom units but capable of dissociating the aldehyde.

6. In a process of effecting abnormal addition of hydrogen sulfide, thesteps of mixing an unsaturated hydrocarbon containing an unsaturatedlinkage between two carbon atoms having a dissimilar number of hydrogenatoms attached thereto, with hydrogen sulfide and a ketone which isdecomposed by light having a wave length above 3000 Angstrom units, andeffecting the reaction photochemically, in the absence of peroxides, andunder the deliberate influence of radiations above 3000 Angstrom unitsbut capable of dissociating the ketone.

7. In a process of effecting abnormal addition of hydrogen sulfide, thesteps of mixing an unsaturated hydrocarbon containing an unsaturatedlinkage between two carbon atoms having a dissimilar number of hydrogenatoms attached thereto, with hydrogen sulfide and an aldehyde which isdecomposed by light having a wave length above 3000 Angstrom units, andeffecting the reaction photochemically, in the absence of peroxides, andunder the deliberate influence of radiations above 3000 Angstrom unitsbut capable of dissociating the aldehyde.

8. In a process of effecting abnormal addition of hydrogen sulfide, thestep of reacting an unsaturated hydrocarbon containing anunsaturated'linkage between two carbon atoms having a dissimilar numberof hydrogen atoms attached thereto, with hydrogen sulfidephotochemically,

in the absence of peroxides, in the presence of a carbonylic compoundwhich is decomposed by light having a wave length above 3000 Angstromunits selected from the class consisting of ketones, aldehydes and acidhalides, and under the deliberate influence of radiations above 3000Angstrom units but capable of dissociating the carbonylic compound underthe operating conditions.

9. In a process of producing di-normal propyl thio-ether, the steps ofmixing proplene with normal propyl mercaptan and acetone, and effectingthe reaction in the liquid state, at a temperature of below about 25 C.,and under the deliberate influence of radiations above 3000 Angstromunits but capable of dissociating the acetone.

10. In a process of producing thio-ethers, the steps of contacting analiphatic hydrocarbon containing an alpha unsaturated linkage with amercaptan, and subjecting said mixture, in the liquid state, at atemperature of below about 25 C., and in the presence of a carbonyliccompound which is decomposed by light having a wave length above 3000Angstrom units selected from the class consisting of ketones, aldehydesand acid halides, to the influence of radiations above 3000 Angstromunits but capable of decomposing said carbonylic compound underoperating conditions.

11. In a process of producing thio-ethers, the steps of contacting anunsaturated hydrocarbon having at least one unsaturated linkage betweentwo carbon atoms having a dissimilar number of hydrogen atoms attachedthereto with a cercaptan and subjecting the reactants photochemically,in the absence of peroxides and in the presence of a carbonylic compoundwhich is decomposed by light having a wave length above 3000 Angstromunits selected from the class consisting of ketones, aldehydes and acidhalides, to

the influence of radiations above 3000 Angstrom units but capable ofdecomposing said carbonylic compound under the operating conditions.

12. In a process for effecting reactions via abnormal addition, thesteps of reacting an unsaturated hydrocarbon having at least oneunsaturated linkage between two carbon atoms having a dissimilar numberof hydrogen atoms attached thereto with a compound selected from theclass consisting of hydrogen sulfide and mercaptans, in the presence ofa carbonylic compound which is decomposed by light having a wave lengthabove 3000 Angstrom units selected from the class consisting of ketones,aldehydes and-acid halides, and efiecting the reaction photochemically,in the absence of peroxides and under the deliberate influence ofradiations. above 3000 Angstrom units but capable of decomposing saidcarbonylic compound.

13. In a process for effecting reactions via abnormal addition, thesteps of reacting an unsaturated organic compound containing anunsaturated linkage between two carbon atoms having a dissimilar numberof hydrogen atoms attached thereto with a compound selected from theclass consisting of hydrogen sulfide and mercaptans, in the presence ofa carbonylic compound which is decomposed by light having a wave lengthabove 3000 Angstrom units selected from the class consisting of ketones,aldehydes and acid halides, and effecting the reaction photochemically,in the absence of peroxides and under the deliberate influence ofradiations above 3000 Angstrom units but capable of decomposing saidcarbonylic compound.

WILLIAM E. VAUGHAN. FREDERICK F. RUST.

